build(spf): build26 from 45504a2b

dist/dev/core/composition/create-composition.js

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+import { signal } from "../signals/primitives.js";
+//#region src/core/composition/create-composition.ts
+/**
+* Create a composition from a set of behaviors.
+*
+* Composition unions the behaviors' declared `stateKeys` / `contextKeys`
+* to know which signals to create. Each signal is seeded from
+* `initialState` / `initialContext` when supplied, defaulting to
+* `undefined`. Behaviors are responsible for writing their own slots
+* once their preconditions are met.
+*
+* Cross-behavior type conflicts (e.g. two behaviors disagreeing on a
+* field's type) surface as a compose-time type error via
+* `ValidateComposition`.
+*
+* @example
+* ```ts
+* const composition = createComposition([resolvePresentation, switchVideoTrack], {
+*   config: { parsePresentation: parseMultivariantPlaylist, initialBandwidth: 2_000_000 },
+*   initialState: { bandwidthState: { fastEstimate: 0, ... } },
+* });
+* ```
+*/
+/**
+* Create a typed signal map for a given set of keys, seeded from an
+* optional partial initial value.
+*
+* Pipeline: `Set` dedupes the iterable (insertion order preserved, so
+* first occurrence wins) → `Object.fromEntries` materializes one
+* `signal()` per unique key, seeded from `initial[key]` or `undefined`.
+*
+* Per-key value types live in TypeScript only — at runtime every signal
+* is `Signal<unknown>`. The boundary cast at the return narrows the wide
+* `Record<PropertyKey, Signal<unknown>>` shape to the caller's expected
+* per-key types from `S`.
+*
+* Used by `createComposition` to derive engine state/context maps from
+* the union of behaviors' declared `stateKeys` / `contextKeys`.
+*
+* @example
+* ```ts
+* interface State { count?: number; label?: string }
+* const state = buildSignalMap<State>(['count', 'label'], { count: 5 });
+* state.count.get(); // 5
+* state.label.get(); // undefined
+* ```
+*/
+function buildSignalMap(keys, initial) {
+	const init = initial;
+	const uniqueKeys = new Set(keys);
+	return Object.fromEntries([...uniqueKeys].map((key) => [key, signal(init[key])]));
+}
+function createComposition(behaviors, options) {
+	const validBehaviors = behaviors;
+	const state = buildSignalMap(validBehaviors.flatMap((b) => b.stateKeys), options?.initialState ?? {});
+	const context = buildSignalMap(validBehaviors.flatMap((b) => b.contextKeys), options?.initialContext ?? {});
+	const deps = {
+		state,
+		context,
+		config: options?.config ?? {}
+	};
+	const cleanups = validBehaviors.map((behavior) => behavior.setup(deps));
+	return {
+		state,
+		context,
+		async destroy() {
+			const results = [];
+			for (const cleanup of cleanups) {
+				if (cleanup == null) continue;
+				if (typeof cleanup === "function") results.push(cleanup());
+				else if ("destroy" in cleanup) results.push(cleanup.destroy());
+			}
+			await Promise.all(results);
+			for (const sig of Object.values(state)) sig.set(void 0);
+			for (const sig of Object.values(context)) sig.set(void 0);
+		}
+	};
+}
+function defineBehavior(behavior) {
+	return behavior;
+}
+//#endregion
+export { buildSignalMap, createComposition, defineBehavior };
+
+//# sourceMappingURL=create-composition.js.map